FIELD OF THE INVENTION
This invention relates to temperature monitoring and control systems for cotton gins and more particularly, to an infrared thermocouple temperature monitoring and control system which operates to notify an operator of a high temperature condition existing at any point along the saw blades and interspaced ginning ribs of the cotton gin saw cylinder assembly. In a preferred embodiment the gin stand heat detection apparatus of this invention is characterized by a pair of infrared thermocouples mounted in spaced, facing relationship in the gin weldment at each end of the saw cylinder assembly of a gin assembly, such that a high temperature condition existing in any one of the saw blades and interspaced ginning ribs of the saw cylinder assembly is detected by the facing infrared thermocouples. The infrared thermocouples are electrically connected to a control panel which includes a set of controls and a visual alarm system for each infrared thermocouple. The infrared thermocouple control panel is also typically electrically connected to the conventional gin stand control panel for terminating operation of the cotton gin in the event of a high temperature condition in the saw cylinder assembly. In a most preferred embodiment of the invention the infrared thermocouples are mounted by means of removable brackets in the main frame weldment of the gin assembly, which main frame weldment also rotatably receives the saw cylinder assembly, the adjacent doffing roller and the fixed ginning ribs, the latter of which register with the saw blades in the saw cylinder assembly. The infrared thermocouple sensors of this invention are unpowered and can measure the surface temperature of materials without touching the materials. The infrared detection elements in the sensors receive heat energy radiated from the objects monitored and convert the heat passively to an electrical potential. A millivolt signal is produced in the sensor and is scaled to the desired thermocouple characteristic. The sensors are solid, hermetically sealed, fully potted systems that do not change either mechanically or metallurgically during service.
In a cotton gin, lint is pulled and separated from the cotton seed by gin saw blades rotating between spaced, fixed ginning ribs. The saw teeth carry the lint through the evenly spaced ginning ribs at the ginning point and the seed is left behind in a roll box. The lint is removed from the saw by a doffing brush mounted on a doffing roller. The gin is typically fitted with 161 saw blades, rotating at a speed of 615 rpm and the saw blades usually have 330 teeth, on 16 inch diameter blades.
One of the problems which has long existed in cotton gins is that of fires which develop when individual tufts or clumps of cotton, commonly called "tags", are trapped between the respective saw blades of the saw cylinder assembly and the corresponding fixed ginning ribs, which are deployed between the individual saw blades of the gin saw. The friction between the tags, rotating saw blades and ginning ribs quickly causes the saw blades and ginning ribs to overheat and warp and sometimes causes a fire in the saw cylinder assembly. Since there is a considerable amount of lint cotton in this lint separation area and air is blown through the cotton gin to aid in the lint separation process, the fire may quickly spread and can easily consume the entire cotton gin. Attempts to provide an early detection system for determining the location of these "hot spots" caused by cotton tags, include using a meter relay to detect the increase in amperage loads on the gin motor when a tag overloads the saw blades. However, the time lag from the onset of the "hot spot" and the detectability of this increase in the amperage load is such that frequently, fires start before the meter relay detection system is operable to detect the problem. In addition to causing fires, such tags can also break or warp the respective ginning ribs extending between the saw cylinder blades, or warp the saw blades themselves and under these circumstances, the entire saw cylinder assembly must be replaced. It has been estimated that 85% of the fires which begin in cotton gins are caused by such tags.
Accordingly, it is an object of this invention to provide a new and improved gin stand heat detection apparatus which is characterized by a pair of infrared thermocouples mounted at each end of the saw cylinder assembly between the saw cylinder assembly and the doffing roller, in facing, spaced relationship with respect to each other for detecting a temperature increase in the saw blades and ginning ribs.
Another object of this invention is to provide a new and improved gin stand heat detection apparatus which includes a pair of infrared thermocouples mounted on the main frame weldment of a gin assembly in facing relationship at each end of the saw cylinder assembly for detection of temperature increases in the saw blades and ginning ribs of the saw cylinder assembly responsive to the entanglement of cotton tags between the rotating saw blades and the ginning ribs.
Yet another object of this invention is to provide a new and improved gin stand heat detection apparatus which includes a pair of infrared thermocouples attached by means of brackets to the main frame weldment of a gin assembly in spaced, facing relationship with respect to each other at each end of the saw cylinder assembly. The infrared thermocouples are connected to a control panel for detecting, displaying and monitoring an increase in the temperature of the saw blades and ginning ribs when cotton tags are randomly and inadvertently lodged between the saw blades and the ginning ribs to create "hot spots" in the saw cylinder assembly.